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High-resolution near-ultraviolet spectra of the yellow hypergiants HR 8752 and rho Cassiopeiae indicate high effective temperatures, placing both stars near the low-T_eff border of the ``yellow evolutionary void.'' At present, the temperature of HR 8752 is higher than ever. For this star we found T_eff=7900+/-200 K, whereas rho Cassiopeiae has T

The Balmer lines of four A Ia-supergiants (spectral type A0 to A3) and fourteen B Ia and Ib-supergiants (spectral type B0 to B3) in the solar neighbourhood are analyzed by means of NLTE unified model atmospheres to determine the properties of their stellar winds, in particular their wind momenta. As in previous work for O-stars (Puls et al. cite

We investigate recent claims that the Hubble sequence of spiral galaxies is scale-free. Fundamental to this investigation is the fact that within the photometric data of 86 spiral galaxies from de Jong & van der Kruit-from which these claims were made-a trend exists between morphological type and bulge profile shape. While late-type spiral bulges

We have applied the InfraRed Flux Method (IRFM) to a sample of approximately 500 giant stars in order to derive their effective temperatures with an internal mean accuracy of about 1.5% and a maximum uncertainty in the zero point of the order of 0.9%. For the application of the IRFM, we have used a homogeneous grid of theoretical model atmosphere

TeV gamma-ray signals from the Crab Nebula and Mkn 501 were detected with the HEGRA CT1 imaging Cerenkov telescope during periods when the moon was shining and during twilight. This was accomplished by lowering the high voltage supply of the photomultipliers in fixed steps up to 13%. No other adjustments were made and no filters were used. Laser